Dip tube for gas-filled cylinder



Sept. 15, 1964 r W. F. SUMMERFIELD DIP TUBE FOR GAS-FILLED CYLINDERFiled July 2, 1962 INVENTOR. E Maw/115' Swrzqwao BY 4 l 4%4, 7 h \wxmmww/477 0Pv United States Patent 3,148,965 DR TUBE FOR GAS-FILLED CYLINDERWilliam F. Summerfield, Garden Grove, Calif., assignor to W. .l. VoitRubber Corp, a corporation of California Filed July 2, 1962, Ser. No.206,703 3 Claims. (Cl. 55-313) This invention relates to dip tubes orturbulence tubes used in gas or air-filled cylinders of the typesuitable for supplying air for self-contained underwater breathingapparatus, also known as SCUBA.

SCUBA cylinders are made of steel and air is pumped into such cylindersunder a pressure of approximately 2250 pounds per square inch gauge.Cylinders of this type commonly develop rust spots along their innersurface and eventually some of this rust flakes off and remains in thecylinder until the latter is thoroughly cleaned. These loose rustparticles can, under normal cylinder usage, find their way into thevalve proper and travel into the pressure reduction regulator system,damaging valve seats beyond repair.

It is also possible that microscopic particles of rust will passcompletely through the filter of the pressure reduction regulator foundin conventional arrangements, and inbed themselves into the delicatevalve seats of the pressure reduction regulator or pass through theregulator into the breathing quality air of the diver himself.

Air supplies of the above type are generally provided with the so-calleddip tubes which are connected to the cylinder and of a shut-ofi valve orreserve valve and in this manner are suspended Within the cylinder fromsuch valve.

The function of the dip tube proper is to extend the high pressure inletof the valve beyond the neck of the cylinder and in this manner preventcondensed water from entering the valve. The liquid Water appears in thecylinder when it becomes condensed from wet air used in filling thecylinder or due to carelessness.

This invention provides dip tubes fitted with a special type of filterand one-way valve for eliminating water and any solid particles thatwould not otherwise be in suspension in the ambient atmosphere fromentering the valve and regulator system. The disclosed dip tubeemploying a special one-way blow-by valve and filter assembly, greatlyreduces the chance of rust or dirt particles damaging the cylinder valveseat or passing into the pressure reduction regulator, or, in extremecases, into the mouth of the user of such SCUBA apparatus.

The compressed air, after it leaves the cylinder and passes through thereserve valve, pressure reducing valves, and pressure regulator, is usedfor breathing purposes and it should be as pure as possible. Also, theentire apparatus between the cylinder and the mouthpiece of a divershould be free of contaminants and water particles to prevent clogging.

It is therefore an object of this invention to provide a dip tube forgas-filled cylinders, the tube being provided with a filter and ablow-by valve.

It is an additional object of this invention to provide a dip tube ofthe above type with a filter and a blow-by valve which becomeseliminated and taken out of the breathing or gas supply circuitaltogether in case the filter becomes clogged, thus eliminating thedanger of suddenly losing the air supply while diving.

Referring to the drawings, the only figure illustrates a sectional Viewof the dip tube, the upper portion of the cylinder and a portion of thereserve valve connected to the cylinder and to the dip tube.

A cylinder is provided with a threaded neck 12 to receive a shut-offvalve 14 having a knob 30 and a stem 31. Valve 14 is provided with anoutput port 16 normally connected to a pressure regulator or regulators.

Patented Sept. 15, 1964 The lower portion of the cylinder valve isprovided with a threaded opening 17 and the dip tube 18 is connected tovalve 14 with its upper threaded end 19. The central portion of the tubeis provided with a bore 20, which terminates at its lower, or inner, endin a circular seat 23 for a sintered metal filter 21 which is fastenedto the tube by means of an expansion ring 22. The filter is composed ofsintered bronze particles, such as grade 40, coated with nickel. Filtersof this type are especially suitable for this use because they provide ahigh degree of filtration and are moisture, corrosion and shockresistant.

Just above the filter seat '23 there is provided an additionaltransverse bore 22 which provides two openings in the tube. The tube isalso provided with a circular recess 24 which acts as a seat for ablow-by valve sleeve 25 which is made of a suitable elastic material.Sleeve 25, in its natural state, has a smaller inner diameter than thediameter of recess 24, and, therefore, sleeve 25 tightly grips the tubeand prevents the air from flowing into the air supply system throughbores 22 and 20 through this blow-by valve during the normal use ofSCUBA equipment. The valve may open, however, when the cylinder 10 isfilled with air. If the rate of flow during the filling cycle issufficiently high to create an appreciable pressure differential acrossthe filter disc 21, the elastic sleeve 25 will expand and allow air toflow through bores 22 and 20 and thus avoid possible rupture of thefilter disc 21. During the air-filling cycle, the air that flows throughthe filter also cleans the filter by dislodging particles caught in itand returning them to the tank.

The blow-by valve 2225 also performs an additional function. If, becauseof some unforeseen malfunction the filter fails to supply air to thebreathing apparatus by becoming clogged, the pressure in the bores 20and 22 drops to a sufficiently low value so as to create a rupturingpressure differential across the elastic band 25 with the result thatband 25 becomes ruptured at one or both ends of bore 22 and air is thensupplied to the breathing apparatus through bore 22 and then bore 20.The filter, then, is bypassed altogether.

Therefore, the blow-by valve 2522 acts first as a well-known one-waycheck valve during the air filling cycle, but it also acts as a safetydevice during the breathing cycle should the filter fail to functionproperly because of clogging.

The length of the tube is made so as to remove the filter and the intakeportion of the tube sufliciently from the neck 12 of the cylinder sothat even when there is a considerable amount of condensed Water in thecylinder it does not reach the filter end of the tube regardless of theattitude (position) of the cylinder. The overall length of the tube isin the order of three inches.

What I claim as new is:

1. A dip tube for a gas-filled cylinder used in underwater breathingapparatus, said dip tube including a hollow tube having a central ductand an outer end having means for fastening said tube to said cylinderand an inner end projecting into said cylinder, said inner end and saidcentral duct terminating in a filter seat, a sintered metal filtermounted within said seat and a blow-by and frangible safety valvebetween said inner and outer ends of said tube for by-passing saidfilter when gas is pumped into said cylinder and for supplying gas fromsaid cylinder in case of failure of said filter, said blow-by and safetyvalve comprising a cross bore piercing said tube and going through saidcentral duct, and an elastomeric band strapped around said tube and oversaid cross bore, said band being pierced by gas pressure within saidcylinder should said filter fail to pass gas from said cylinder intosaid tube.

2. A dip tube for a gas filled cylinder, said dip tube comprising anelongated tube having a first central bore and first and second ends,said first end having means for connecting said dip tube to the outletend of said cylinder, said second end having a' seat, a filter mountedwithin said seat, said filter closing off said first central bore at thesecond end of said tube, a transverse second bore intersecting saidfirst bore above said filter and said second end, and an elastomericband surrounding said tube at said second bore for closing ofl? saidsecond bore, said second bore and said band acting as a blow-by andsafety valve for said dip tube, said second bore and said blow-by valveby-passing said filter when gas is pumped into said cylinder and whensaid filter fails to supply gas from said cylinder.

3. A self-contained underwater breathing apparatus including agas-filled cylinder providing breathing atmosphere for a diver, saidcylinder having valve means and a dip tube having first and second ends,said first end being the outer end attached to said valve means, theimprovement in said dip tube comprising a filter mounted at and withinthe second inner end of said dip tube, said second inner end projectinginto said cylinder, and a blow-by and safety valve between said firstand second ends of said dip tube, said blow-by and safety valvecomprising a cross-bore piercing said tube and an elastorneric bandstretched over said tube and said cross-bore to bypass said filter whensaid filter is being filled with said gas, said band being pierceable bygas pressure at the cross-bore if said filter becomes plugged up duringuse of said apparatus.

References Cited in the file of this patent UNITED STATES PATENTS1,185,309 Haeseler May 30, 1916 2,554,343 Pall May 22, 1951 2,630,920Kerr Mar. 10, 1953 FOREIGN PATENTS 733,853 Germany Apr. 3, 1943

1. A DIP TUBE FOR A GAS-FILLED CYLINDRICAL USED IN UNDERWATER BREATHINGAPPARATUS, SAID DIP TUBE INCLUDING A HOLLOW TUBE HAVING A CENTRAL DUCTAND AN OUTER END HAVING MEANS FOR FASTENING SAID TUBE TO SAIDCYLINDRICAL AND AN INNER END PROJECTING INTO SAID CYLINDER, SAID INNEREND AND SAID CENTRAL DUCT TERMINATING IN A FILTER SEAT, A SINTERED METALFILTER MOUNTED WITHIN SAID SEAT AND A BLOW-BY AND FRANGIBLE SAFETY VALVEBETWEEN SAID INNER AND OUTER ENDS OF SAID TUBE FOR BY-PASSING SAIDFILTER WHEN GAS IS PUMPED INTO SAID CYLINDER AND FOR SUPPLYING GAS FROMSAID CYLINDER IN CASE OF FAILURE OF SAID FILTER, SAID BLOW-BY AND SAFETYVALVE COMPRISING A CROSS BORE PIERCING SAID TUBE AND GOING THROUGH SAIDCENTRAL DUCT, AND AN ELASTOMERIC BAND STRAPPED AROUND SAID TUBE AND OVERSAID CROSS BORE, SAID BAND BEING PIERCED BY GAS PRESSURE WITHIN SAIDCYLINDER SHOULD SAID FILTER FAIL TO PASS GAS FROM SAID CYLINDER INTOSAID TUBE.